Carburetor



Aug. 2, 1932- 'w. M. THOMAS CARBURETOR Filed June 20. 1930 gwuatovWilliam /1. Thom&1 i

Patented Aug. 2, 1932 s'r'rss UNITE VI'ILLIAM M. THOMAS, OF ALBUQUERQUE,NEW MEXICO, ASSIGNOR OF ONE-FOURTH TO FRED WQLEE AND ONE-FOURTH T0 BRYANG. JOHNSON, BOTH. OF ALBUQUERQUE,

NEW MEXICO Application filed June 20,

This invention relates to a device for intimately mixing a liquid and agas, and more particularly to the type of mixers known as carburetors,which are extensively used on internal combustion engines forautomobiles for mixing a liquid fuel such as gasoline with a gas, suchas air, with which it will explosively react under proper conditions.

In the type of internal combustion engine ordinarily used inautomobiles, the engine is so designed that its speed and the consequentspeed of the car may be varied within a rather wide range by merelyvarying the amount of explosive mixture supplied to the engine by thecarburetor. The carburetor, therefore, must be designed to supply thisexplosive mixture at a rate which may be varied at the will of theoperator.

In order that the operator may control the carburetor to cause it tosupply to the engine an amount of explosive mixture just sufficient tooperate the engine at the desired speed, the ordinary carburetor has inthe passage through which the gas passes from the carburetor to theinternal combustion engine a butterfly valve which the operator of theautomobile may control manually, opening or closing this valve in orderto accelerate or slow down the engine.

The function of the carburetor then is to supply to this passage amixture, usually of gasoline and air, in sufficient quantities and incorrect proportions at all speeds. The usual type of carburetor attemptsto accomplish this result by injecting into the air passage a finelydivided spray of the liquid fuel. A common method of doing this consistsin maintaining in the carburetor a supply of liquid fuel at a constantpressure by the use of the conventional float chamber. From this floatchamber the fuel is supplied to a nozzle or nozzles which discharge intotheair passage before it reaches the butterfly valve. The discharge endsof these nozzlesare generally so located and so directed that the fuelwill be dischar ed therefrom only when a suction is create at theirdischarge ends by the movement of air through the-passage. As themanually. controlled valve is'opened wider, the movement of air throughthe pas- CARBURETOR 1930. Serial No. 462,536.

sage becomes more rapid, thesuction greater and hence the amount of fuelsucked through the nozzles into the air in the passage is also greater.r j I It may be noted here, however, that the explosive mixture used byan internal combustion engine produces its maximum effect only when thepercentage of fuel in the explosive mixture is exactly right for theparticular speed at which the engine is operating and that the samemixture will not give maximum power at all speeds. With a system ofcarburetion such as above set out, ,it is the usual practice to adjustor proportion the fuel nozzles so that a proper amount of fuel isinjected into the air to give maximum efficiency at the average runningspeed. With such systems there is no assurance nor any reason to believethat the proper mixture will be supplied to the engine over anyappreciable range of speeds. The fact that a proper mixture is notsupplied to the engine at all times is clearly shown by the fact thatfrequently when the engine is running at an idling speed, and thebutterfly valve quickly opened, the engine will stall because animproperly proportioned mixture has been supplied thereto. 7

In some of the carburetors ofthe aforementioned'type, in order toproduce a finer dispersion of the fuel in theair, the passage in whichthe dispersion is made has been formed in the shape of a Venturi tube,that is with'a smaller or constricted section which tapers graduallyinto a section of larger cross-section or diameter. The nozzles fromWhich the fuel is dispersed or atomized are then located near thesmallest part of the constriction, and as the expansion of the air uponpassing the constriction increases the suction upon these nozzles, theymay conse-' quently be made smaller and still supply the same amount offuel. It has been found that these smaller nozzles, together with-theexpansion of the air, cause a more intimate mixture of the air and fueland consequently a better and more powerful explosive mix-' ture.

The present invention relates to means for V obtaining anintimatemixture of the air and i" liquid fuel, and to such means as will alsoensure that the proportion of the dispersed fuel in the explosivemixture will at all times be exactly that required for maximumefiiciency, regardless of the speed at which the engine is running. Thisis accomplished by a novel construction of that section of passagethrough which the air or other gas travels before it reaches themanually operated butterfly valve, and in which section of passage thegasoline or other fuel is atomized or dis persed in the air.

As already stated, by varying the shape of this passage and the spacingand arrangement of nozzles in the passage, it has been found possible todraw from the nozzles an amount of fuel equal to almost any desiredpercentage of the air passing through the passage. However, the amountof air passing through this passage varies with the speed of the motorand for the most eflicient operation it is essential that as the speedof the motor or rate of flow of air through this passage varies theamount of fuel drawn from the nozzle or nozzles be varied in such anamount that there is supplied to the motor, at whatever rate of speed itis revolving, a supply of ex plosive mixture containing exactly theright proportion of fuel and in which the fuel is completely dispersedin the air.

In the present carburetor, the section of passage through which the airtravels before reaching the manually operated valve contains acompartively short constricted portion which flares abruptly into a muchwider section forming a comparatively steeply tapered shoulder. In thistapered shoulder are a series of air passages which are constantlymaintained unobstructed and through which a part of the incoming air isat all speeds directed toward the center of the passage, and angularlyonward through the passage to ward the manually operated valve. Thesepassages open at their other ends into a chamber which, in turn,communicates directly with the main passage on the opposite side of theconstricted portion. The constricted portion is so shaped as to form, inconjunction with the main passage, two concentric passages, one throughthe center of the con strict-ed portion which is generally the largerair passage, and a second surrounding passage which supplies air to theopenings through the shoulder and provides means for separating aportion of the incoming air for feeding the supplemental openings in theshoulder, and also for providing the necessary resistance to the airpassing through said openings- The fuel nozzles terminate near theconstricted part of the passage and are di rected toward the point atwhichthe streams of gases flowing through the openings in the shoulderconverge. It has been found that such a construction not only gives avery F fine atomization of the fuel, but also causes the fuel to besupplied at exactly the proper proportion for maximum efliciencyregardless of the speed at which the engine is running.-

For a specific embodiment of the applicants invention as applied to acarburetor of the type ordinarily used on automotive vehicles referencemay be had to the accompanying drawing in which:

Fig. 1 illustrates a carburetor of applicants new improved type shown inside elevation with certain parts in cross section;

Fig. 2 is a top sectional view of the same construction taken on theline 2-2 of Fig. 1.

In the drawing the carburetor is composed of two castings 1 and 2 whichhouse a suitable float mechanism in chamber 3 which float mechanismsupplies liquid fuel to the mixing device at a constant pressure. Thisfloat chamber is of the conventional type and is not shown in detail.The castings 1 and 2 further provide an air passage 4 through which airis adapted to enter at the end 5 of the air passage which is located inthe casting l and through which passage the air is conveyed to an exit 6in the casting 2 from which it is led to the internal combustion engine.

Near the end 5 of this passage is located the conventional choke valve 7which is adapted to reduce or cut off the supply of incoming air andnear the exit 6 of the passage is located a butterfly valve 8 forregulating the amount of explosive mixture supplied to the engine.Adjacent the butterfly valve 8 is a small opening 9 through which asmall amount of explosive mixture is supplied for idling.

Located within the passage 4 in the vertical portion thereof andextending partly into both of the castings 1 and 2 is located a sleeve10 through which the incoming air passes upwardly and during. whichpassage it is mixed with the required amount of liquid fuel. Near thelower end of the sleeve 10 is located a constriction 11 which is ringshaped and which forms a short constricted opening 17 through which thegreater portion of the air must pass on its way to the engine. Thisconstricted portion is of general Venturi shape but flares abruptlyabove its point of greatest constriction forming a shoulder 12 in thesleeve 10 and flares somewhat less below the point of greatestconstriction. Openings 13 situated in the shoulder formed by theconstriction direct air passing through them in converging linesupwardly and toward the center of the sleeve 10. At their opposite endsthe openings 13 open into an annular recess 14 formed between the lowerpart of the constriction 11 and the outer shell of the sleeve 10. Theconstriction 11 and the sleeve 10 are illustrated as one piece but mayobviously be made in two parts to simplify manufacture. Nozzles 15 and16 are located in the bottom of the passage 4 and extend upwardly intothe constricted opening 17, ter- 1 plosive mixture to the engineminating at points adjacent the point of greatest constriction andsupplying liquid fuel to the incoming air at this point. p

The major steps in the operation of this device are fairly obvious. Theair passes through the passage 4 through the constricted opening. 17 andthe recess 14 and openings 13 into the upper part of the sleeve 10 and,

then by the butterfly valve 8 and into the engine. As the air passesthrough the opening 17 into the. upper part of sleeve 10 itis permittedto expand suddenly and creates a by the engine. IIowever, the velocityof air through these openings is also governed in part by the resistanceofiered by the openings to the passage of air therethrough and byproperly proportioning the size of the openings 13 and the recess 14 tothe size of the constricted opening 17 it has been found possible to soproportion the flow of air through the openings 13 and the constrictedopening 17 that the proper proportion of air will pass through theserespective openings at all speeds to draw from the nozzles 15 and 16 thedesired amount of fuel for proper engine performance and produce theproper mixing of the atomized or vaporized fuel and air at all speeds. 7

One of the distinct advantages of this construction is in the shortconstricted portion which causes a minimum of resistance to the incomingair and therefore supplies the ex quickly and with a minimum ofresistance.

The device is relatively simple in construction, all of its parts arefixed and no levers, cams, gears or springs are present to get out oforder and yet merely by the suction produced in the upper part of thesleeve 10 this novel constructionadjusts the proportion of fuel and airto be mixed and provides a means for intimately mixing them in thedesired proportions under all normal operating conditions of the engine.I

Having thus described my invention, I claim: v

1. In a carburetor for internal combustion engines, a main air passagetherethrough, means forming a constricted portion within said passage,said means having an outwardly and onwardly directed shoulder leadingfrom the constricted portion to the wall of said passage, a fuelsupplying nozzle in said 7 main air passage, said nozzle having itsdischarge end terminating adjacent the portion of greatest constriction,an air chamber,

opening into the main air passage at all engine speeds, surrounding atleast a part of the constricted portion of the main air passage, saidshoulder having openings there-' through adjacent the constrictedportion for the continuous introduction of an auxiliary supply of airfrom'said surrounding chamber into the fuel and air 'mixturejin the mainpassage, the openings in said shoulders emerging adjacent the point. ofgreatest constriction in said main air passage;

2. In a carburetor, a main passage, a

shoulder in said main passage forming a constricted opening therein, achamber opening into said main passage and surrounding at least aportion of said shoulder at one end thereof, the other end of saidshoulder flaring from said constricted openingto the wall of saidpassage at an angle greater than 45 to the center line of said passage,said shoulder having a plurality of small supplemental openings formingthe only connection be- I tween said chamber and the passage on theother side of said shoulder.

In testimony whereof I aflix my signature. WILLIAM M. THOMAS.

